WO2014179571A1

WO2014179571A1 - Compression-resistant shock absorber piston seal

Info

Publication number: WO2014179571A1
Application number: PCT/US2014/036373
Authority: WO
Inventors: David L. Ruhlman; Paul PRZYBYL
Original assignee: Ride Control LLC
Current assignee: Ride Control LLC
Priority date: 2013-05-02
Filing date: 2014-05-01
Publication date: 2014-11-06
Anticipated expiration: 2015-11-02
Also published as: CN111197637A; EP2992241A4; KR102138819B1; CA2911202C; CN105339696A; CA2911202A1; EP2992241B1; AU2014259799B2; US10480605B2; EP2992241A1; MX2015015268A; AU2014259799A1; US20140326556A1; MX382341B; KR20160018504A; CN111197637B; HK1215966A1

Abstract

A shock absorber including a cylinder having a first chamber and a second chamber where at least one of the first chamber and the second chamber includes a fluid. A piston is configured for reciprocal movement within the cylinder and defines at least one through-hole for enabling the fluid to move between the first and second chambers. A floating disc and a floating retainer are each movably connected to the piston, the floating disc and the floating retainer defining a space between the floating disc and the floating retainer, the space having a cross-sectional area. A seal element is seated in the space and has a cross-sectional area equal to the cross-sectional area of the space where an entire surface of the seal element engages and forms a seal with an inner wall of the cylinder during the reciprocal movement of the piston.

Description

COMPRESSION-RESISTANT SHOCK ABSORBER PISTON SEAL

PRIORITY CLAIM

The present non-provisional application claims priority to and the benefit of U.S. Provisional Application No.61/818,558 filed on May 2, 2013, and U.S. Provisional Application No.61/889,737 filed on October 11, 2013, which are hereby incorporated by reference in their entireties.

BACKGROUND

Hydraulic telescoping shock absorbers are comprised of precision tubes, rods, valves, seals and bearing elements filled with hydraulic oil. The piston valve, and more specifically, the valve body, separates the valve into a rebound side and a compression side and controls the rebound and compression flow of the oil to provide controlled damping. A seal element or seal around the valve body is designed to minimize or eliminate oil bypassing the valve body which affects the performance of the shock absorber. The force developed by the pressure drop of the oil across the piston valve is transmitted by the piston rod to a vehicle body to which the shock absorber is attached.

The piston valve (also known as the "cage valve") is unique to all other damping valves in that the seal element, housed between a floating retainer 10 and floating disc 11, moves relative to the valve body 12 by hydraulic pressure in the damper compression direction against a spring 13 to control compression damping forces. FIG. 1 shows the valve in the closed position and FIGs. 1A and 4 show the valve in the open position. In particular, the floating disc 11 identified in the drawings is shown in the closed and opened positions, respectively allowing a different flow path through the valve body 12. The compression and rebound flow patterns are identified in FIGs. 1, 1A and 4.

The piston valve or cage valve is also unique in that it enables oil flow from the center of the piston valve to the end of the piston rod 14 by being threaded directly to the end of the piston rod without an additional fastener, i.e. nut, bolt, screw, etc. secured to the piston rod.

The prior art seal element 15 design shown in FIGs. 1, 1A and 2 has a round cross-section with a single small contact surface area against the cylinder wall 16. This smal l contact area does not provide an adequate seal with the cylinder wal l and over time deteriorates , res ulting in ins ufficient sealing ability and pressure leakage which negatively affects the performance of the shock absorber. Additionally, the round cross-section seal element 15 deforms into an oblong cross-section during compres sion of the s eal element, resulting in a s in gle contact point with the cylinder wal l 1 6. Repeated reciprocal movement of the s eal element 15 in the cylinder causes the porti on of th e s eal element at the single contact point to rub against t he cylinder wall 1 6 and wear o ut prematurely. A s the seal elem ent 1 5 wears, the seal formed between the s eal element and the cylind er wall 16, i. e. , the effectiveness of the s eal, decreas es th ereby reducing the function and effectiven ess of the sh ock absorber cross-section. SUMMARY

A shock absorber seal with an increased sealing surface area is therefore desirable to reduce l ow speed variation and for enhancing shock absorption during rebound and compression.

An improved seal element for a shock absorber is provided that reduces low speed oil leakage between the piston sealing el ement an d the cylinder wall by changing the geometry and fit of the seal element and how it interfaces with the piston carrier and inner cylinder.

In an embodiment, a shock absorber is provided that includes a cylinder having a first chamber and a second chamber, where at least one of the first chamber and the second chamber includes a fluid. A piston is configured for reciprocal movement within the cylinder and defines at least one through-hole for enabling the fluid to move between the first and second chambers. A floating disc and a floating retainer are each movabfy connected to the piston, the floating disc and the floating retainer defining a space between the floating disc and the floating retainer, the space having a cross-sectional area, A sealing element is seated in the space and has a cross-sectional area equal to the cross-sectional area of the space where an entire surface of the sealing element engages and forms a seal with an inner wall of the cylinder during the reciprocal movement of the piston.

In another embodiment, a shock absorber is provided and includes a cylinder having a first chamber and a second chamber, where at least one of the first chamber and the second chamber includes a fluid. A piston having a valve body that separates the first chamber and the second chamber is configured for reciprocal movement within the cylinder, the valve body defines at least one through-hole for enabling the fluid to move between the first and second chambers. A floating disc and a floating retainer are each movab!y connected to the valve body, where the floating disc and the floating retainer define a space between the floating disc and the floating retainer. A sealing element is seated in the space and has a square cross-section where an entire first surface of the sealing element engages at least one inner surface of the floating disc and the floating retainer, and an entire second surface of the sealing element engages and forms a seal with an inner wall of the cylinder during the reciprocal movement of the piston.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary cross-section of a shock absorber having the prior art design;

FIG. 2 is a fragmentary cross-section of the shock absorber of FIG. 1 showing the shock absorber in a closed position;

FIG. 3 is a perspective view of a prior art seal element; FIG. 4 is a perspective view of an embodiment of the present seal element;

FIG. 5 is an enlarged, exploded perspective view of the floating disc, the seal element of FIG . 4 and the floating retainer;

FIG. 6 is a fragmentary cross-section view of a shock absorber including the seal element of FIG. 4; and

FIGs. 7(a)-7(f) depict vertical cross-sections of further embodiments of the seal element.

DETAILED DESCRIPTION

Referring to FIGs. 1 -7(f), to improve the sealin g abi l ity and effectiveness of the present seal element, more surface area against the cylinder wall is provided. Rather than a single point of contact from a round seal element or seal element with a circular or round cross-sec tion, a flat s urface abutting the cylinder wall is used for increasing th e slidin g surface contact between the seal element and the cylinder wall and thereby enhancing the seal formed between the seal element and the cylinder wall (FIG. 4). Specifical ly, the present sea! el em ent preferably has a square cross-section to enhance the seal between the seal el em ent and the cylinder wall as described below. It shoul d be appreciated that the seal element may have variety of different cross-sections including a flat surface for enhancing the surface contact between the sealing element and the cylinder wall and improve its sealing ability. An example of a sealing element having a cross-section with a flat contact surface is a quadrilateral- or polygon-shaped sealing element including a trapezoid-, rectangle- or square-shaped sealing element (FIG. 5). Additionally as shown in FIG. 7, it should be appreciated that a sealing element may have a triangular shaped cross-section or any polygonal shape which provides a flat surface to abut and form a seal with the cylinder wall 14 may be used.

As shown in FIGs. 5 -6 , the shock absorber 20 includes a piston valve 22 having a valve body 24 biased by a spring 27 such that the valve body reciprocates within a cyl inder 26 during rebound and compression of the shock absorber. The valve body 24 includes a seal assembly 25 havin g a floating disc 28 , a floating retainer 30 and a seal element 34, where the disc and the retainer move relative to each other and also relative to the cylinder 26, and define a space 32 therebetween for retainin g the present seal element, such as a seal element 34 having a squ are cross -section. The seal element 34 is preferably made of N itrile Butadiene Rubber (N BR) and has a 90 durometer hardness. It should be appreciated that the seal element 34 may be made of any suitable materi al including, but not limited to, NBR, HNBR, Viton , Torlon, PTFE, Nylon, Delrin, or any other suitable polymer, elastic or hyper elastic material. It should also be appreciated that the present sealing element may have any suitable hardness.

D uring rebound and compression of th e shock absorber 20, the seal element 34 contacts an inner surface 36 of a cylinder wall 38 of the cylinder 26 to form a seal w ith the wal l . As shown in FIG s . 4 an d 5 , the seal el em ent 34 has a flat or pl anar outer s urface 40 that ful ly contacts the opposing flat inner surface 36 of the cylinder wall 38 and thereby increases th e s urface contact between the seal el ement and the wall as compared to convention al seal el em ents havi ng round cross-sections . Also, during rebound and compression of the shock absorber 20, the floating disc 28 and the floating retainer 30 move relative to the valve body 24 and to each other due to a biasi ng force on th e retain er by a biasing m ember, s uch as a compression spring or a coi l sprin g 42 (FIG. 6). Both the fl oating disc 28 and the floating retainer 30 h ave gen erally flat or planar inner surfaces 44 an d 46 th at engage the corresponding flat outer surfaces 40 (FIG, 5 ) of the seal element 34 , res ulting in the enti re surfaces of the floating disc 28 and/or the floating retainer 30 and the sealing element being in contact with each other. The full side or full surface contact betw een the floating disc 28 and th e sea! element 34 and/or the floating retainer 30 and the sealing element 34 more uniformly distributes the force or pres sure on the sealing element across the entire surface of the sealing el ement , as oppos ed to a sm al l er contact area or single point contact area provided by convention al seal elem ents.

Further, as seen in FIGs . 5 and 6, the square cross-section or square shape of the seal element 34 corresponds to the shape of the space 32 defined between the floati ng disc 28 and th e floating retainer 30 such that clearance between the seal element 34 and the floating disc and floating retainer is reduced compared to the conventional circular cross-section seal elements . In the preferred embodim ent, the present seal element 34 i s dimensioned to substantially fill the space 32 defined between the floating disc 28 and the floating retainer 30. More specifically, and referring to FIG. 5 , the two plan ar seal-engaging surfaces 48 of the floating retainer 30, defining a general "L"-shape, and the planer seal -engaging s urface 50 of the floating disc 28, combine to define the space 32 , which has a generally polygonal or square vertical cross -section. Thus, the preferably square cross - sec tion of the present seal element 34 subs tanti al ly fil ls the space 32. At the same time, the resi lience of the seal element 34 accomm odates the relative squeezing movement of the floating disc 28 towards the floating retainer 30 during shock absorber operation. The increased surface contac t between the seal elem ent 34 and the floating disc 28 and retainer 30 and the reduction in the space between these components combine to decrease the amount of deformation of the seal element during the reboun d an d compression of the shock absorber 20. Less deformation of the seal element 34 helps to maintain the enhanced surface area seal between the seal element and the cylinder wall 38. Additionally, the compl ementary dimension al relationship between th e present sea! element 34 and the associated space 32 prolongs the fife of the seal element, as the wear on the surfaces of the seal elem ent are m ore uni form than with a single point contact or smaller contact s urface area between the seal element and the w all 38. In thi s regard, the improved design of th e seal element 34 h as increased the life of the seal el em ent by approxim ately sev en times (7X) over conventional seal elements from 200,000 cycles to 1 .4 million piston cycles in the shock absorber.

A s described above, the increased surface area contact between the present seal element 34 and the cylinder wall 38 and the reduction in the compression and resulting deformation of the seal element minimizes the pressure leakage between the two sides of the valve body that may result from a single point of contact or small contact area as with conventional seal elements having round cross-sections. Further, the increased contact s urface area minimizes l osses due to w ear and deformation and results in more consistent absorption of shock forces over time.

While particular embodiments of the shock absorber and piston seal have been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A shock absorber comprising:

a cylinder having a first chamber and a second chamber, at least one of said first chamber and said second chamber including a fluid ;

a piston configured for reciprocal movement within said cylinder and defining at least one through-hole for enabling the fluid to move between the first and second chambers;

a floating disc and a floating retainer each movably connected to said piston, said floating disc and said floating retainer defining a space between said floating disc and said floating retainer, said space having a cross-sectional area; and

a seal element seated in said space and having a cross-sectional area equal to said cross-sectional of said space,

wherein an entire surface of said sea! element engages and forms a seal with an inner wall of said cylinder during the reciprocal movement of said piston.

2. The shock absorber of claim 1 , wherein said piston includes a valve body and said floating disc and said floating retainer are attached to said valve body,

3. The shock absorber of claim 1 , wherein said seal element has a polygonal cross-section ,

4. The shock absorber of claim 1 , wherein said seal element has a square cross-section.

5. The shock absorber of claim 1 , wherein said floating retainer has an L-shaped cross section.

6. The shock absorber of claim 1 , wherein said seal element is made of rubber.

7. The shock absorber of claim 1 , wherein said seal element is made of Nitrile Butadiene Rubber,

8. The shock absorber of claim 1 , wherein said sea! element has a durometer hardness of 90,

9. The shock absorber of claim 1 , wherein said fluid is hydraulic fluid.

10. A shock absorber comprising:

a cylinder having a first chamber and a second chamber, at least one of said first chamber and said second chamber including a fluid;

a piston having a valve body that separates said first chamber and said second chamber and being configured for reciprocal movement within said cylinder, said valve body defining at least one through -hole for enabling the fluid to move between the first and second chambers ;

a floating disc and a floating retainer each being movably connected to said valve body, said floating disc and said floating retainer defining a space between said floating disc and said floating retainer; and

a seal element having a square cross-section seated in said space, wherein an entire first surface of said seal element engages at least one inner surface of said floating disc and said floating retainer, and an entire second surface of said seal element engages and forms a seal with an inner wall of said cylinder during the reciprocal movement of said piston.

1 1. The shock absorber of claim 10, wherein said floating retainer has an L-shaped cross section.

12. The shock absorber of claim 10, wherein said sea! element is made of rubber,

13. The shock absorber of claim 10, wherein said seal element is made of Nitrile B utadiene Rubber,

14. The shock absorber of claim 12, wherein said seal element has a durometer hardness of 90.

15. The shock absorber of claim 13, wherein said seal element has a durometer hardness of 90.

16. The shock absorber of claim 1 , wherein said fluid is hydraulic fluid.